"Cities in six continents joined up to form the world's largest alliance to combat climate change on Wednesday, a move intended to help making ground-level changes to slow global warming."

"The US Food and Drug Administration on Monday approved the first human trial of an experimental Zika vaccine, according to a joint announcement by the two companies behind the new therapy."

"A solar-powered airplane took off from New York's John F. Kennedy International Airport early Monday, in a bid to have the Solar Impulse 2 craft cross the Atlantic Ocean and land in Spain on Thursday."

"At night, just after the full moon, teams of scientists dive beneath the waves to study one of the planet’s most prolific and mysterious rites of reproduction."

"A report released Monday by the nonprofit watchdog group Global Witness claims that 2015 was the deadliest yet for people who sought to protect their land, forests and rivers from mining, logging and dams."

"Pregnant women who become infected with the Zika virus are at risk of having babies with the severe birth defect known as microcephaly, regardless of whether they have symptoms of the disease, according to a new report."

"The streak continues: May was record warm for the globe, according to NASA data released Monday."

"President Francois Hollande on Wednesday signed a bill formally ratifying the Paris climate agreement reached last December by nearly 200 countries to limit global warming."

"Arctic sea ice shrank to its lowest level in 38 years last month, setting a record low for the month of May and setting up conditions for what could become the smallest Arctic ice extent in history, according to National Snow and Ice Data Center data released Tuesday."

"More than one-third of the world's population can no longer see the Milky Way because of man-made lights."